Telegraphic transmitter.



PATENTED AUG. 9, 1904.

fiwelzior Horace (:KMarZin,

APPLIOATION FILED MAY 7, 1904.

H. G. MARTIN. TELEGRAPHIG TRANSMITTER.

no MODEL UNITED STATES Patented August 9, 1904.

PATENT Orrice.

TELEGRAPHIC TRANSMITTER.

SPECIFICATION forming part of Letters Patent No. 767,303, dated August 9, 1904.

Application filed May '7, 1904. Serial No. 206,795. (No model.)

To all whom it may concern:

Beit known that I, HORACE Gr. MARTIN, a citizen of the United States, residing at Brooklyn, in the county of Kings and State of New York, have invented certain new and useful Improvements in Telegraphic Transmitters, of which the following is a specification, reference being had to the drawings accompanying and forming a part of the same.

In a patent granted to me on June 30, 1903, No. 732,648, I have shown and described a novel form of telegraphic transmitter the essential features of which are a key, a vibrator, and suitable electrical connections by means of which a movement of the key in one direction closes the circuit continuously to line, while a movement of the key in the 0pposite direction closes the line-circuit through the vibrator, which operates to send a succession of impulses continuing as long as the key remains in such position.

Briefly stated, the object of the invention is to enable operators to send Morse signals by means of a key, but by a very greatly-reduced number of movements of the latter, and thus to provide a simple and effective method of sending that avoids the intense nervous strain involved in the operation of the ordinary Morse key in rapid work. Inasmuch as the nature, object, and advantages of this system are dwelt upon at length in my patent referred to, it is unnecessary to repeat them herein, it being suflicient now to point out that the first of the above-described movements of the key which effect prolonged closures of the line is used to send the dashes, while the movement in the opposite direction, which closes the line through a vibrator, sends the dots of the Morse code. The length of the spaces and dashes and the number of the dots are thus under the direct control of the. operator, while the length of the dots and their rapidity of succession is determined by the adjustment of the period of vibration of the vibrator. In the several forms of instruments shown in my said patent in illustration of the principle of the invention the vibrator-magnet is in a circuit controlled by the key, is set in operation by the current which is caused to flow in its circuit by a given movement of said key, and thrown out of operation by the interruption of such current. I have found that this plan is in many respects the most reliable and effective; but I have also devised another way of carrying out the invention in which a circuit-controller having a predetermined period of its own is directly controlled by the movement of the key-that is to say, is mechanically released or set in operation and restrained or prevented from its normal operation of sending successive short impulses over the line by the disengagement and engagement therewith of the key itself. Such a device may be made more cheaply and is more simple in construction; but for many purposes it is a very desirable instrument and secures the main advantages of my novel system. This form of transmitter, which I designate as semi-automatic, is exemplified in any combination of a key which by a movement in one direction sends an impulse to line proportional in length to the duration of the contact thus effected and an automatic circuit breaker or controller of the general nature of a vibrator or buzzer which operates to make and break the circuit at a substantially uniform but comparatively rapid rate and which is normally restrained from operation by the key, but released by the movement of the latter in a direction opposite to that utilized for sending dashes. Obviously many forms of vibrator, mechanical and electrical, may be utilized for this purpose; but in illustration of the general principle I have shown in the accompanying drawings a device in the nature of a pendulum which by the engagement of the key is normally held at such a point in its path of swing that when released by the withdrawal of the key it will be free to vibrate. This vibrator is utilized to make and break a circuit and send dots over the line, the number sent in succession being determined by the length of time the key is held out of engagement with the pendulum. In connection'with the pendulum I may use an electromagnet the circuit of which is controlled by the oscillations of the pendulum itself; but this is not essential in any case in which, as with a pendulum released at some point to either side of the center of oscillation, the device possesses in itself the capability of movement which may be utilized to periodically make and break a circuit.

Referring now to the drawings, Figure 1 is a plan view of the instrument, showing the circuit connections. Figs. 2 and 3 are similar views of modifications of the same, and Fig. 1 is a detail showing the key-lever in section.

As a convenient form of key I use a plate or bar 1, held against the flat surface of an arm or post 2 by means of a flat spring 3 and a spiral spring 4:, which surrounds a stud 5. The key bar orlever lcontains a slot through which the stud 5 passes, and the compression of the spring 1 is regulated by a screw-nut 6 on the end of the stud. By this means the key-lever is held in its central or normal position, but may be readily moved from side to side about the point 2 as a fulcrum. A hardrubber plate 7 and a head 8 are secured to the key-lever and are of any form which makes it convenient for the operator to grasp them between the thumb and fingers. The keylever 1 is bent at its free end at right angles and carries a set-screw 9. The end of this screw lies in the path of a vibrator which in this case consists of a rod or bar 10, supported by a fiat spring-plate 11 on a stud 12. A weight or bob 13 is adjustably attached to the bar 10 to vary its period of vibration. In its normal position the key-lever holds the pendulum-bar to one side of its normal center of oscillation, with the spring 11 under light tension. If the key be shifted so as to suddenly withdraw the set-screw from engagement with the pendulum, the latter will at once start vibrating and will continue in motion for some time. This movement is taken advantage of to make and break either of the line or a local circuit by attaching to the bar a light contact-spring 14%, which touches a contact-stop 15 when the bar swings over sufficiently to that side. The circuit connections to the bar 10, stop 15, and key-lever 1 are made in any suitable and well-known way, so that when the key is shifted by the operator to the right the vibrator will send dots over the line, but when the key is turned to the left it will come in contact with a stop 16 and send a prolonged impulse to line. A convenient arrangement of circuits for this purpose is shown in Fig. 1, in which 25 is a wire leading from a battery 26, and 27 is the line-wire. The wire 25 is connected to the stop 15 and also to the key-lever, while the line-wire is connected to stop 16 and also to the pendulumlever 10. By this means the battery-currents will be sent to the line from either the stop 15 or the key-lever 1, according as contact is made between stop 15 and spring 1 1 or between the key-lever and stop 16. The screwstop 9, carried by the lever 1, is of insulating material or insulated from the lever in case the pendulum-lever is of conducting material or the spring 1 1 not insulated from it.

In Fig. 2 substantially the elements are shown, and the operation is not materially affected by the modifications introduced. The key-lever in this figure is shown as seated on two spiral springs 16, inserted in recesses in the post 2 on opposite sides of the fulcrum of the key. These springs take the place of the flatspring 3 of Fig. 1. I have shown in this figure also an electromagnet 17 in the circuit of the pendulum and stop 15. When the pendulum has been released by the key and closes the circuit between the spring 14 and stop 15, the magnet 17 is energized and exerts an attraction for the pendulum, which ceases the instant the circuit is broken by the separation of the contact-points. This imparts a more positive swing to the pendulum and maintains the amplitude of its vibrations. A short circuit around the magnet, maintaining a resistance 18 and switch 19, may be used to cut the magnet out when so desired.

The arrangement shown in Fig. 3 differs from that of Fig. 2 only in having a local circuit 20 for energizing the magnet 17. This circuit contains a local battery 21. and is made and broken by an additional spring 22 on the pendulum and a stop 23. This arrangement takes the magnet 17 out of the main or sending circuit.

From the above description of the construction and mode of operation of the form of transmitter to which my present application relates it will be obvious that the vibrator and the specific means for engaging and releasing the same by the key may both be varied in many details without departure from the invention.

hat I claim is- 1. In a telegraphic transmitter, the combination with a circuit-controller capable of.

making and breaking a circuit at a uniform rate, of a key normally engaging said controller and preventing it from operating, and a contact for said key, the key being capable of two movements from its normal position, one of which withdraws it from engagement with the controller, while the other brings it into engagement with its contact, as set forth.

2. In a telegraphic transmitter, the combination with an automatic circuit-controller capable of making and breaking a circuit at a uniform rate, of a key normally engaging said controller and preventing it from operating, means for holding said key in its normal position of engagement with the controller, and a contact-stop for said key, the key being capable of movement in opposite directions from its normal position, by one ofwhich it releases the controller and by the other of. which it engages the contact-stop, as set forth.

3. In a telegraphic transmitter, the combination with an automatic vibrating circuitwhereby the latter is permitted to intermitcontroller having a defined period of oscillatently make and break the circuit, and by the IQ tion, of a key normally engaging the controlother of which it engages with the contactler, and preventing it from vibrating, and a stop, as and for the purposes set forth.

5 contact-stop for said key, the key being capa- HORACE G. MARTIN.

ble of movement in opposite directions from Witnesses: its normal position, by one of which it is With- M. LAWSON DYER, drawn from engagement with the controller, I S. S. DUNHAM. 

